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Lesson Overview
10.1 Cell Growth, Division,
and Reproduction
THINK ABOUT IT
When a living thing grows, what happens to
its cells?
What is there about growth that requires
cells to divide and reproduce themselves?
Limits to Cell Size
What are some of the difficulties a cell faces as
it increases in size?
The larger a cell becomes, the more
demands the cell places on its DNA. In
addition, a larger cell is less efficient in
moving nutrients and waste materials
across its cell membrane.
Information “Overload”
Living cells store critical information in DNA.
As a cell grows, that information is used to
build the molecules needed for cell growth.
As size increases, the demands on that
information grow as well. If a cell were to grow
without limit, an “information crisis” would
occur.
Information “Overload”
Compare a cell to a growing
town. The town library has a
limited number of books. As the
town grows, these limited
number of books are in greater
demand, which limits access.
A growing cell makes greater
demands on its genetic “library.”
If the cell gets too big, the DNA
would not be able to serve the
needs of the growing cell.
Exchanging Materials
Food, oxygen, and water enter a cell through the cell
membrane. Waste products leave in the same way.
The rate at which this exchange takes place depends
on the surface area of a cell.
The rate at which food and oxygen are used up and
waste products are produced depends on the cell’s
volume.
The ratio of surface area to volume is key to
understanding why cells must divide as they grow.
Ratio of Surface Area to Volume
Imagine a cell shaped like a cube. As the length of the sides
of a cube increases, its volume increases faster than its
surface area, decreasing the ratio of surface area to volume.
If a cell gets too large, the surface area of the cell is not
large enough to get enough oxygen and nutrients in
and waste out.
Traffic Problems
To use the town analogy again,
as the town grows, more and
more traffic clogs the main
street. It becomes difficult to get
information across town and
goods in and out.
Similarly, a cell that continues
to grow would experience
“traffic” problems. If the cell got
too large, it would be more
difficult to get oxygen and
nutrients in and waste out.
Division of the Cell
Before a cell grows too large, it divides into two new
“daughter” cells in a process called cell division.
Before cell division, the cell copies all of its DNA.
It then divides into two “daughter” cells. Each
daughter cell receives a complete set of DNA.
Cell division reduces cell volume. It also results in an
increased ratio of surface area to volume, for each
daughter cell.
Cell Division and Reproduction
How do asexual and sexual reproduction
compare?
The production of genetically identical
offspring from a single parent is known as
asexual reproduction.
Offspring produced by sexual reproduction
inherit some of their genetic information from
each parent.
Asexual Reproduction
In multicellular organisms, cell division leads
to growth. It also enables an organism to
repair and maintain its body.
In single-celled organisms, cell division is a
form of reproduction.
Asexual Reproduction
• Asexual reproduction is reproduction that
involves a single parent producing an offspring.
The offspring produced are, in most cases,
genetically identical to the single cell that
produced them.
• Asexual reproduction is a simple, efficient, and
effective way for an organism to produce a large
number of offspring.
• Both prokaryotic and eukaryotic single-celled
organisms and many multicellular organisms can
reproduce asexually.
Sexual Reproduction
• In sexual reproduction, offspring are
produced by the fusion of two sex cells – one
from each of two parents. These fuse into a
single cell before the offspring can grow.
• The offspring produced inherit some genetic
information from both parents.
• Most animals and plants, and many singlecelled organisms, reproduce sexually.
Comparing Sexual and
Asexual Reproduction
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